PROJECT ABSTRACT/SUMMARY We have made significant gains in the correct classification of Spanish-English bilinguals with language impairment though the identification of clinical markers of impairment. Yet a hurdle in reducing the health disparities associated with language impairment in bilingual populations is the need to establish developmental milestones that can serve as the foundation for goal setting and evaluation of progress as a function of language intervention. We know that experiential factors (age of acquisition and language use) interact with bilingual language outcomes. But we do not have a detailed picture of qualitative and quantitative differences between bilingual children with language impairment and their typically developing peers in the semantics and morphosyntax domains. The proposed project will translate the knowledge base regarding clinical markers of impairment, experiential factors, and knowledge of the linguistic systems of English and Spanish to the development of a clinical tool. The focus of the tool is to benchmark language learning in bilingual children growing up in the US context. Thus, the major aim of this project is to develop and validate a criterion referenced inventory and set of probes in Spanish and English. These will be useful for intervention planning and to measure change as a function of language intervention. This tool will target 4-10 year old Spanish English bilinguals with and without language impairment. We will achieve this aim by 1) developing and evaluating an extension of our existing item set; 2) conducting an item tryout study to establish an item set for testing semantic and morphosyntactic performance profiles; and 3) field testing and validating a inventory and probes for profiling patterns of mastery in bilingual children with language impairment that is normed to account for age and language experience. To achieve these milestones, we will recruit 1200 bilingual children between the ages of 4 and 10 years of age from representative U.S. bilingual populations both in regard to dialect and SES. Using a modified matrix model, children will complete a battery of test items that tap key aspects of lexical-semantic and grammatical knowledge in English and Spanish. To make this tool maximally useful in clinical settings, we will program the task to be delivered by computer so that appropriate targets are selected based on the child's age and language experience and that sufficient targets are administered to accurately establish mastery and non-mastery. This research will form the foundation of a clinical tool that can be used by clinicians to establish goals and to document progress as a function of language intervention. This work will further our research in language impairment, especially with bilingual children, because we will document a broad profile of lexical semantic and morphosyntactic skills over a wider age range than is usually studied. The tools developed will also be useful for researchers who need to benchmark children's performance in developmental and intervention studies.